take into consideration that the 360 (at least currently) doesnt support the standard 24'' or higher resolution of 1900x1200 (16:10) so youll have to use the resolution of 1280x768 which is the closes resolution the 360 supplies to 16:10 (its not exasctly 16:10, but its the closest).

if youre gonna play a console only i would say get a HDTV, if you want to play computer games only, i would recommend a monitor. if youre gonna play both, i would say monitor, because an HDTV doesnt double well at all as a functional computer screen, even though a computer monitor doesnt make a perfect console display.